Multistage fan for suction cleaners



Nov. 10, 1953 D. B. TSCHUDY MULTISTAGE FAN FOR SUCTION CLEANERS 3 Sheets-Sheet 1 Filed Dec. 7, 1950 QT a n ATTORNEY.

1 Nov. 10, 1953 D. B. TSCHUDY 2,658,665

MULTISTAGE FAN FOR SUCTION CLEANERS Filed Dec. 7, 1950 3 Sheets-Sheet 2 mmvron. Donaid B.Tschud,g

ATTORNEY.

Nov. 10, 1953 D. B. TSCHUDY MULTISTAGE FAN FOR SUCTION CLEANERS 3 Sheets-Sheet 3 Filed Dec. 7, 1950 DJ a m 6 mm m VB T N T I a Fig. 4

BY fi y Patented Nov. 10, 1953 MULTISTAGE FAN FOR SUCTION CLEANERS Donald B. Tsohudy, Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application December 7, 1950, Serial No. 199,689

18 Claims. (Cl. 230117) This invention relates to a multi-stage motorfan unit for Suction cleaners in which the usual interstage separator between the two stages of the fan is dispensed with and the necessary passages are formed in the main fan casing itself.

According to the present invention the fan casing also forms a housing for the commutator of the motor and the discharge passage from the second stage of the fan discharges directly into the commutator housing where the air expands to cool the commutator and passes longitudinally therefrom through the entire motor to cool both the stator and the roor.

As a result of the arrangement of the present invention the total length of the motor-fan unit is decreased appreciably without a corresponding decrease in the efficiency of the motor-fan unit as such.

According to another feature of the present invention the multi-stage fan proper is formed of a single central rotating disc having blades secured to opposite sides thereof to form the multistage rotor. The necessary shrouds are secured to the outer sides of the fan blades on opposite sides of the central disc to form fan eye openings.

According to the present invention an outer fan chamber is provided which discharges into ducts in the main fan casing leading to the eye of the second stage impeller on the opposite side of the main fan body. The second stage of the fan discharges into passages in the main fan casing spaced annularly from the discharge passages of the first stage, which passages lead to the commutator housing.

According to another feature of the present invention the exhaust ports leading from the two stages of the fan are provided with cut-01f vanes so that the velocity head of the moving mass of air at the discharge of each stage is converted to a static pressure head so as to add its effect to the total suction head created.

Another feature of the present invention is the positioning of the expansion and exhaust chambers of the first and second stages, axially coextensive with each other, and the positioning of both pairs of air passages axially coextensive with each other and with the commutator brush housing whereby the axial depth of the motor-fan unit can be materially reduced.

According to another feature of the present invention the main fan casing forms a housing for the commutator end of the motor rotor, a support for the motor casing, a partial housing for the multi-stage fan impeller, a pair of annularly spaced arc-shaped expansion chambers and a pair of annularly spaced arc-shaped exhaust chambers positioned between the expansion chambers in communication with complementary expansion chambers so that both occupy the entire annulus at the discharge side of the first stage fan. The main casing also forms a pair of annularly spaced arc-shaped expansion chambers and a pair of annularly spaced arc-shaped exhaust or static head chambers positioned between the expansion chambers in communication with complementary expansion chambers so that both occupy the entire annulus at the exhaust side of the second stage of the impeller. The second stage annulus is positioned radially inwardly of and axially coextensive with the first stage annulus. Two pairs of radially extending, annularly spaced, axially coextensive air passages are positioned axially rearwardly of the first and second stage expansion and exhaust chambers. One pair connects the exhaust chambers of the first stage to the suction side of the second stage thereof, and the other pair connects the exhaust or static head chambers of the second stage to the interior of the housing at the commutator end of the motor rotor. A pair of annularly spaced radially extending commutator brush housings are positioned axially coextensive with and between the first and second stage air passages.

Other objects and advantages of this invention will become apparent, as the description proceeds, when taken in connection with the accompanying drawings in which:

Figure 1 is a longitudinal cross-sectional view of the multi-stage motor-fan unit of the present invention showing the air flow path from the first stage to the second stage;

Figure 2 is a front view of the motor-fan unit of this invention with the front cover removed showing the first stage of the fan in section and the remainder of the unit in dotted lines;

Figure 3 is a longitudinal cross-sectional view showing the air flow path from the second stage to the commutator housing;

Figure 4 is an end view of the motor unit of this invention showing the general outline of the first air passages from the first to the second stage and from the second stage to the commutator housing; and

Figure 5 is a cross-sectional view through the motor housing showing the motor cooling air passages.

Referring to the drawings, the reference numeral Ill represents the main casing of the fan preferably in the form of an integral casting. The reference numeral l l represents the stator the reference numeral 20is secured to shaft I8 by means of a nut I9. The fan 20 comprises a main sheet metal disc 2I having first and second;

stage fan blades 22 and 23, respectively, secured to the front and rear sides thereof. Annular shrouds 24 and 25 are secured to the outer sides of the blades 22 and 23, respectively. Asshown, the blades 22 and 23 are of arcuate formation and are curved to trail in thedirection of rotation.

At the discharge of the first stage thefancasing I is divided annularly into two expansion chambers '26 and two exhaust-or static head chambers 21 which together occupy substantially the entire annular extent ofithe casing-at that radius.

Radially, inward of the expansion chambers-26 and 21 the casing: I0 is againdividedannularly into two expansion chambers 28 andtworexhaust or static .head chambers29- whichalso-occupy substantially the'entire annular ex tent of the casing III- at that radius. Spaced axially rearward of theexpansion chambers 26 and 28 and the exhaust chambers 21 and-28 the main casing I0-is divided annularly into-pairs of radially-extending air -passages 30--and 3| and a.

pair of housings 32 for'the commutatorbrush holders 33 which together occupy substantially the entire annular extent ofthe casing III-at that axial position;

The exhaust chambers 21 and 2 9 communicate with theexpansionchambers 25.and 28 respectively-by way of ports: 26: and-. 28 respectively.

Adjacent the commutatorhousing I3 the radialpassages 30 communicate-with ports-34 leadingvto-theeye 35 0f .the second stage of the-fan.

Ports 36 extend through the wall ofthe forwardly bulgedhousing I3 and communicate with radial passages 3| leading. from the exhaust of the second' stage-of the fans.

A cover plate-38 havinga fan eye 39 cooperates with the main fan casing II) to form thewfirststage =fan chamberand the expansion and :exhaust chambers-26 and*2'l,- the casing. I0 being extended outwardlyat 40 to prevent-bypassingof air through port 26'.

The stator I I is enclosed in'a'casing 4'I clamped between the main casing. I0 and the end cap 12;

Stator coils 42 are-woundon the poles 43 of the" The stator II doesinot completely-fill:

stator II. the-casing whereby openings =44 are formed for the circulation of air thereover.- Openings 45 in which the coils 42 are-woundralso provide for air circulation'throughthe interior of the motor.

At thejunction of the-expansion chambers 26'- and the exhaust chambers 21 and at the-junction of the expansionsch'ambers 28 and the exhaust chambers 29 the main casingis provided with'extensions to form out-off vanes and-.41 respectively, for a'purpose to be'explained' hereinafter;

Operation Uponenergization of the-motor-the fan 20 is,

rotated at high speed. The first stage vanes 22 draw air-inwardly-through the fan eye 39-and discharge it into theexpansion chambers 26 .at-

a high velocity. The cut-oif vanes 46 will pre-.-

vent the high velocity air from by-passing chambers 21. The high velocity air will impinge against the cut-off vanes 46 and the velocity head will be changed into a static head in the chambers 21 resulting in a net increase in the suction head produced by the first stage of the fan.

From the expansion chambers 26 the air will pass through chambers 21, radial passages 30 and ports 34 to the eye35 of the second stage of the fan 20. The second stage blades 23 will add to the. velocity head of the air stream and discharge it into expansion chambers 28. The high velocity air impinges against the cut-off vanes 41 and the velocity :headis changed to a static head in chambers '29 as.in:th'e first stage to add to the net suction: head produced.

The air then passes through radial passages 3I and ports 36 into the commutator housing I3 where it expands to cool the commutator I4. The air then passes backwardly through the passages and 45 tocool the rotor I5 and stator I I and is'disoharged'through, openings in the end cap I2.

The-present invention is particularly suited for use in suctioncleaners. be madeconsiderably shorter than in the ordinary multi-stage fan. In addition, the commutator-.canebe positioned-very close to the front bearingso as tohave better running characteristicsand so that it willbe maintained in a much cooler condition than it positioned at the opposite pellernsecured to the extended .end of said shaft;

said impeller comprising a centrally positioned circular disc havingicentr-ificallyacting impeller blades securedlto the :opposite sides thereof; and

means secured tosaidcasing and operating in' cooperation. therewith .and with said impeller for forming a multi-stage fan; said means, casing and impeller being arrangedto form at least one expansion chamber at the .exhaust sideof the first stageof said impell'e'nto-form a static head 1 chamber for the first stage of said impeller in communication with said expansion chamber, to

form ducts communicatingsvith' said statichead chamber and leading tothe suction side of the second stage of said limpeller, to form at least one expansion chamber at the exhaust side: of

the second stage .of said. impeller, to-forma static head 'chamberfdrthe 'second stage-of said impeller in communication. .with the expansion chamber'of the second stage .of said impeller and to form exhaust ducts in communication with the static headnchamber of the secondIsta-ge of said impeller.

2. In a fan according to claim 1 .in which the expansion chamber and static head chamber of the first stage of said impeller are positioned radially outwardly of the expansion chamber and static head chamberof the-second stage of said impellereand in axial alignment therewith.

3. Inca fan according to claim 2 iin which-each of said statichead chambers is positionedan-- The motor-fan unit cannularly of its corresponding expansion chamber and in axial alignment therewith.

4. A motor-fan unit comprising; an integrally formed frame having a central opening; a motor stator supported on one side of said frame; a motor rotor rotatably supported by said frame and stator; said rotor having a shaft extended through said central opening; a fan impeller carried by the extended end of said shaft; said fan having a set of radially extending blades on each side thereof so as to form a multi-stage impeller with the inlet sides of the stages facing in opposite directions; means on said frame forming a fan eye and a casing for the outer set of blades; said frame being formed with a first expansion chamber for receiving air from the exhaust side of the outer set of blades, a first passage leading form the first expansion chamber to the rear of said impeller and communicating with the suction side on the inner set of blades, a second expansion chamber for receiving air from the inner set of blades and a second passage leading from said second expansion chamber to said central opening so as to direct air over said rotor and stator.

5. In a multi-stage fan, a cylindrical body having a forwardly bulged front wall, a shaft mounted for rotation in said wall with one end thereof extended forwardly beyond said wall, a fan impeller secured to the extended end of said shaft for rotation therewith, said impeller including a circular disc having fan blades secured to each of its opposite faces and annular fan eye forming shrouds secured to the outer edges of said blades,

said impeller and body cooperating to form first and second stages of a multi-stage fan, a first pair of arc-shaped annularly spaced expansion chambers formed in said body at the periphery of the first stage of said impeller, a first pair of arc-shaped annularly spaced static head chambers formed in said body each annularly spaced from and communicating with the adjacent of said expansion chambers, a first pair of radially extending annularly spaced air passages formed in said body each communicating in its outer end with the corresponding of said first static head chambers and at its inner end with a fan eye of the second stage of said impeller, a second pair of arc-shaped annularl spaced expansion chambers formed in said body at the periphery of the second stage of said impeller, a second pair of arc-shaped annularly spaced static head chambers formed in said body each annularly spaced from and communicating with the adjacent of said second expansion chambers, a second pair of radially extending annularly spaced air passages formed in said body each communicating at its outer end with a corresponding one of said second static head chambers and at its inner end with a port formed in said body and communicating with the interior of the chamber formed by said forwardly bulged front wall.

6. In a multi-stage fan according to claim 5 in which said first expansion and static head chambers are axially coextensive with each other and together form a complete annulus at the discharge side of the first stage of said impeller.

'7. In a multi-stage fan according to claim 6 in which said second expansion and static head chambers are axially coextensive with each other and with said first expansion and static head chambers and are positioned radially inwardly of the latter.

8. In a multi-stage fan according to claim 7 in which said first and second air passages are 6 axially coextensive with each other and are posi tioned axially rearward of said first and second expansion and static head chambers.

9. In a multi-stage fan according to claim 7 in which said body is provided with three forwardly extending radially spaced walls which form the inner and outer walls of said first and second expansion and static head chambers.

10. In a multi-stage fan according to claim 9 in which the disc of said impeller is extended beyond the fan blades to form the front wall of said second expansion and static head chambers.

11. In a multi-stage fan according to claim 10 including a plate extending from the outer of said Walls to the eye of the first stage of said impeller forming the front wall of said first expansion and static head chambers.

12. In a multi-stage fan according to claim 5 in which said first and second air passages are axially coextensive with each other and are axially spaced rearwardly of said first and second expansion and static head chambers.

13. A multi-stage motor-fan unit comprising; an integrally formed main body including a transverse wall separating the fan chamber from the motor chamber, a rearwardly extending cylindrical wall and three forwardly extending radially spaced annular walls; a motor casing secured to the rear edge of said rearwardly extending wall, a motor end cap secured to the rear end of said casing, a motor stator positioned centrally within said casing, a shaft carrying a motor rotor including a commutator rotatably mounted in bearings located centrally in said transverse wall and said end cap respectively, said commutator being positioned at the end of said shaft adjacent said transverse wall, said shaft being extended forwardly beyond said transverse wall and having a multi-stage fan impeller secured thereto, said impeller having first stage fan blades secured to its front face and second stage fan blades secured to its rear face; said body being formed with at least one first stage discharge chamber between the outer and inner of said forwardly extending walls and communicating with the exhaust side of the first stage of said fan, with at least one first stage radially extending air passage communicating at its outer end with the first stage discharge chamber and at its inner end with the suction side of the second stage of said fan, with at least one second stage discharge chamber between the inner and intermediate of said forwardly extending Walls and communicating with the discharge side of the second stage of said fan, and with at least one second stage radially extending air passage communicating at its outer end with said second stage exhaust chamber and at its inner end with the interior of the motor chamber at the commutator end thereof.

14. A multi-stage motor-fan unit according to claim 13 in which said body is formed with at least one first stage expansion chamber be tween the outer and intermediate of said forwardly extending walls and with at least one second stage expansion chamber between the inner and intermediate of said forwardly extending walls, and with said first and second stage expansion chambers communicating at one end with the exhaust of the first and second stages of said fan respectively and at the other end with the first and second stage exhaust chambers respectively.

15. A multi-stage fan unit according to claim 13 in which said first and second stage air passages-"are coextensive with ea'ch other axially -'of' said=--sha'ft: andannularly spaced from each a muIti-sta ge motor-fan unit-comprising; a cy lindrical body having a forwardly bulged transversewall, arearwardly" extending cylindrical wallof-less diameter than said body and three:

forwardly extending cylindrical Walls spaced radially'from eachotherys'aid transverse wall having a shaft bearing receiving opening in the bulged portion thereof andforming a housing 'for receiving-the commutator end'of a motor rotor; said -'rea-rwardly extending cylindrical wall forming a support for a motor casing; a first pair of arc-shaped'annularly spaced expansion "chambers formed in said body-between the intermediate and outerof said forwardly extending cylindrical walls, a first pair of arc-shaped annularly spaced exhaust" chambers'formed in said 1 body between the intermediate and. outer of said forwardly extending-walls andlying an nularly between and axially coextensive with said first pair of' expansion chambers, *a first pair of radially extending annularly spaced'air passages formed in said body "spaced *axially rearwardly of said first expansion" and exhaust chambers, a second pair ofarc-shaped annularly spaced expansion chambers formed in said body between the inner-and intermediate of said forwardly extending walls axially coextensive withsaid first expansion and exhaust chambers, asecond pair of-arc shapedannularly spaced exhaust chambers formedin said body between the inner and intermediate-of" said forwardly extending walls lying between and axially coextensive with said'secondpair of expansion chambers; a second pair of'radially'extending annularly spaced air passages formed in said body between and axiany coextensive with said first pair of air passaes'g-eachof said exhaust chambers communicating with ;--an'-- expansion 'cha'mber' 'and "'each" of said air passages commumcating with an "exhaust chamber, outlet ports formed in s'aidbody" for said first airpassages extending "through said transverse wall radially outwardly of; said bearing receiving 10 opening and 'outlet 'ports formedin said body extending through-'--the sidewalls of the bulged portion of said transverse *Wall immediatelyto therear of said bearing Teceivingopening.

- 17.'Anarticle of "manufactureaccording to claim 16 in which the intermediate and inner or said" forwardly extending walls" are provided -w1th a cut-off vane atthe junction 'betwe en'said expansion and exhaust'chambers.

18.'An' article of manufacture accbrdina to claim 16 in whicn'said bo dy'is'iormedwith'ra- 'di'ally extending "commutator brush housings between each set of first andsecondair passages.

"DONALD'BJTSCHUDY.

References Cited. in the files of this patent UNITED STATES" PATENTS 

